online.wsj.com - In hot markets where bidding wars are common, the property-appraisal process has been short-circuiting transactions, spurring some would-be buyers to walk away.

A few forces are at work. First, many homes are being appraised at a lower price than what buyers have offered on a house. That is because home values are improving so fast in competitive, high-priced markets that "comps," recent sales of nearby homes with comparable characteristics, haven't kept up. When the appraisal comes in low, the buyers either lose the loan or must quickly make up the difference with a higher down payment.

When Kellie and Michael May decided to refinance their home in the New York suburbs, they wanted to take advantage of historically low interest rates. But before landing a new 30-year fixed-rate mortgage, they had to get through a home appraisal.

But the appraisal came back roughly $70,000 less than the $1,230,000 the Mays were expecting, and too low to support their new loan.

reuters.com - "The reality is that the appraiser is only there for 30 minutes at most," says Brian Coester, chief executive of CoesterVMS, a nationwide appraisal management company based in Rockville, Maryland. "The best thing a homeowner can do to get the highest appraisal possible is make sure they have all the important features of the home readily available for the appraiser."